Railway electric track-circuit system



R. W. TARRANT. RAILWAY ELECTRIC TRACK CIRCUIT SYSTEM.

APPLICATION FILED NOV. 4, 1919.

Patented July 6, 19%.,

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l ll lib l i l llll l RAILWA'EZ' ELECTRIC TRIlCll-GIRC'UIJU KSZ'S'IEM.

Specification of Letters lEatent.

Patented duly ll, ltl lll Application filed November l, 1519. Serial No.835,697.

To all "whom it may concern:

I lie it known that l, ltnunnn W LLIAM fliinimn'r, a subject of thelilinp; of Great llritain, residing at London, lilnglanchhave inventednew and useful Improvements in ltailway Electric lrack-Uircuit Systems,of which the following is a specification.

This invention relates to railway electric track-circuit systems forgoverning the automatic actuation of trallic-controlling ap paratus, andhas for its object to provide means for enabling). continuous electriccurrent, normally flowing in a track-circuit, to be automaticallyconverted into pulsating); current, when the value oil the continuouscurrent exceeds a predetermined limit, as the result (for example) ofthe resistance between the rails of the traclesection being re ducedbelow a predetermined value.

For this purpose it has already been proposed to employ at the batteryend of the track-circuit (i. c. the end remote from the usualtraliic'controlling track-relay) what may be termed an electromagneticinterrupter or pulsator, comprising a switch and an electromagnet forcontrolling the same, whereof both the switch and the winding of theelectromagnet are interposed in series in the track-circuit; thearmature of the electromagnet serving to actuate the switch-blade insuch manner that the switch, normally held closed, will be momentarilyopened under the increased. attractive o'lliort exerted upon thearmature when the current-output oil. the battery rises beyond. a

predetermined value in consequence of the resistance between the railsbeing reduced below a predetermined limit as the result, tor example, ofthe ballast and sleepers becoming wetted by rain, or oi? a vehicleentcrlng the traclcssection and thus short-circuiting the battery. Theopening of the switch momentarily breaks the track-circuit, or reducesthe value of the current flowing therein, so that the switch isimmediately ire-closed, with the result that the same cycle oil.operations is repeated as long as the reduction in the resist ancebetween the rails continues; the pulsator-armature and switch vibrating"1neanwhile and the normally-continuous current in the track-circuitbeing converted for the time being; into a rapidly-pulsating current asa result of the making and breaking of the circuit.

According to the present invention the pulsator-armature is in the termoi a still vibratory reed which constitutes also the sw tch, and whichis suitably polarized so as to cause the attractive elliort exerted bythe electromagnet to be modified (i. 0. either reinforced, or partiallycounteracted) as may be found desirable. lduch reinforcement may beobtained by. making the armaturereed niecl'ianically and magneticallyintegral with the core of the pulsator-coil; while either reinforcementor counteraction may be obtained by cinu'espondingly arranging thewinding of a relatively high-resistance coil encircling thearmature-reed and interposed in a permancntly-closed connection betweena pole of the track-circuit battery and the end of one of thetrack-rails. The latter arrangement serves also to prevent completeseverance of the traclccircuit, and the occurrence of sparking, when theswitch is opened; sparking being also preventable by other means, suchas the use of a condenser interposed in a separate connection which maybe either substituted for, or provided in parallel. with, thearmature-polarizing circuit. The armature-reed should be sullicientlystill to be free from liability to oscillate (so as to break the circuitwhich is normally closed) under the influence of the strongestmechanical vibrations to which it may be exposed in consequence, forexample, of the passage of trains over the track.

ln; the accompanying d awingrs, Figures '1, F2, 3 and 4i illustrate, in.each case diagrammaticall tour typical examples oil. the application ofthe invention; similar reference symbols denoting corresponding parts inall the figures.

In each. case, A and l3 are the rispective track-rails, (l is thetraclecircuit battery, and l) the usual traflic-controllinp;track-relay, while E is the electromagnetic pulsator of the presentinvention; this pulsator com prising an electromagnet il and a switch llin the form of a still vibratory reed which constitutes the armature ofthe clectroman;- net. The reed-switch G, which is shown as mechanicallyand magnetically integral with the electromagnet'core, extends from thatend f of the core of the magnet F to which it is permanently fixed,beyond the opposite or polar extremity f of the magnet-core so as to besubject to the attractive effort exerted thereat the free end of theswitch G normally resting by its own elasticity against a contact it soas to be free to move toward the Ill till

lllll lllt pole of the magnet. It is obvious that the reed instead ofconstituting the switch may actuate a switch.

Referring now to Figs. 1 and 2, it will be seen that in each of thesethe opposite ends of the winding 7 of the electromagnet F arepermanently connected, respectively, to the adjacent end of the rail Aand to one pole of the battery C, the opposite pole of the battery beingpermanently connected to the fixed end of the reed-switch G (or to thecontiguous end f of the core of the magnet F) while the resting-contacth of the switch G is permanently connected to the adjacent end of therail 13. So long as the currentoutput from the battery G is of thenormal working value, the'attractive effort exerted by the electromagnetF is insufficient to dis turb the reed-switch G from its resting-contactit, so that the current in the track-circuit remains constant andcontinuous, and the reed G does not vibrate. lVhen, however, theinter-rail resistance falls below a predetermined limit, owing to (say)the presence of a train in the track-section of the ballast and sleepersbeing wet, the current output of the battery G will increase so far asto permit the attractive effort exerted by the electromagnet F to raisethe switch G momentarily from its resting-contact 7b. This has foreffect to momentarily break the track-circuit or reduce the value of thecurrent therein, so that the switch G at once returns to itsresting-contact it; the same cycle of operations being repeated as longas the interrail resistance remains below the predetermined value, sothat the reed-switch Gr continues to vibrate and the continuousbattery-current is converted for the time being into a rapidly-pulsatingcurrent.

In Fig. 1, the occurrence of sparking at the resting-contact h, isprevented by the interposition of a condenser j, in a bridgeconnectionbetween the contact 71. and the connection from the battery C to thereedswitch G. In Fig. 2, the same result is obtained by the similarinterposition of a relatively high-resistance winding 9, coiled aboutthe armature G, this winding 9 being employed either in place of or inaddi tion to the condenser 7', which latter is shown in dotted lines inFig. 2. The fact of the armature-reed G being, as in all the samplesillustrated, magnetically integral with the core of the electromagnet F,causes it to be polarized so that the attractive effort exerted upon itis reinforced. This reinforcement may be either increased or diminishedby the use of the winding 9, which thus affords means for enabling thecoming into action of the pulsator to be adjusted as may be foundnecessary.

Referring now to Figs. 3 and l, it will be seen that the arrangementstherein illustrated differ from those shown in F igs. l and 2,respectively, only in the following particulars. In Figs. 3 and a, whileone end of the winding f, of the clcctromagnet F is permanentlyconnected to one pole of the battery C, the opposite end of this windingis permanently connected to the fixed end of the reed-switch Gr (or tothe contiguous end 7' of the magnet F) the opposite pole of the battery(3 being permmiently connected to the adjacent end of the rail ll, andthe resting-contact /i being permanently connected to the adjacent endof the rail i\. In Fig. 3, sparking is prevented by the interposition ofa comlcnser y' in a bridge connection between the resting contact l1 andthe connection from the winding lo the reed switch G, while in Fig. 4:,the same result-is obtained by the similar interposition of a relativelyhigh-resistance winding coiled about the armature (l, this winding beingemployed either in place of or in addition to the condenser j, whichlatter is shown in dotted lines in Fig. 4.. The action of thearrimgcments shown in Figs. 3) and l is similar to that of thearrangements shown in Figs. 1 and 2.

The invention enables several advantages to be obtained. Thus forexample, it is well known that, on a vehicle entering a tracksectionunprovided with special currenteconomizing means, the short-circaitingof the track-circuit battery (consequent on the virtual cutting-out ofthe track-relay by the train-shunt) causes so great an increase incurrent-consumption that serious waste occurs in the event of thetrack-section re maining occupied for a considerable period. The presentinvention, however, provides in effect an automatic currentcconomizerserving to reduce the current eonsmnplion throughout the entire periodduring which the track-section is occupied, for the reason that theconversion of the normally-continuous current into a pulsating currentis equivalent to the introduction of a resistance into thetrack-circuit, so that the rate olcurrent-consuinption when thetrack-section is occupied will never exceed, and can even be made lessthan, the rate normally prevailing when the track-section is empty.

The reduction of current, which thus automatically follows on areduction of the inter-rail resistance below a predetermined limit, alsosecures the fallirig-away of the armature (Z of the track-relay D (Figs.1 to 4) occurring with greater certainty at the required moment, for thereason that the train-shunt not only reduces the current flowing in thetrack-relay coils (as is usual), but also increases the current throughthe pulsatorcoil f, whose energization breaks the battery-circuit at 71this feature, which tends to prevent intermittent picking-up" of thetrack-relay armature d in the event remote of wide variations occurringin the value of the current flowingin the train-shunt, remainingunal'l'ectedso long as such current-- value is sufficiently high tocausei lm reedswitch i tovibrate. 1 l levertheless, the elliciency oi.the continuous-current track-relay ll is not diminished, tor the reasonthat, under normal conditions 6. so long; as the Y traclesection isunoccupied or the inter-rail till d ll

resistance does not fall below the predeten mined limit), the currentenergizing the traclerelay always remains continuous current.

'llhe pulsator, lll may be adjusted. to pro duce pulsations, in thecurrent flowing in the track-circuit, at any ciiirrent value above thatrequired to cause the track relay armature al to fall away; but thepulsator will not come into operation until the current through thetrztclccircuit battery G has attained tl 1o 1n'edeterini nod value;hence, when the intern-ail resistance 'lalls almorrnally owing to somecause (such as rain on the permanent way) other than the presence of avehicle in the track -section, the pul- .ra tor ill will producepulsations in the trackcircuit, and thus reduce the current flowint:therein, but not necessarily to such an extent as to cause thetrack-relay armature (Z to fall away. lnthis sense, therefore, thepulsator E constitutes in e'l'lect an automatic regulatinrgresistance,or constantly-acting; economizer, governing the value oil? the currentwhich is permitted to flow from the traclncircuit battery (3 into thetraclccircuit.

Having now particularly described and ascertained the nature oi? my saidinvention and the manner in which the same is to be performed, lldeclare that what ll claim is z- 1. in a railway electric track-circuitwhich includes on the one hand the winding); oil a trailic-controllinorelay interposed in series between the trachails at one end oii atraclcsection and on the other hai'ul a source of continuous current, anelectro magnet winding, and. a normally-closed switch controlledthereby, all in'terynised in series between the track-rails at theopposite end of the track-section, the combination of a core for saidelectromagnet wind in t, and an armature therefor formed by a Vibratoryreed which is mechanically and magnetically integral with said core andwhich also constitutes said switch; substantially as and for the purposeset forth.

2. lln a railway electric track-circuit which includes on the one handthe winding oi? a tratlic-controlling relay interposed in series betweenthe traclerails at one end of a traclcsection, and. on the other hand asource of continuous current, an electromagnet winding, and anormally-closed switch controlled. thereby, all interposed in seriesbetween the track-rails at the opposite end of the track-section; thecombination of a core for said electromagnet winding, an armaturetherefor formed by a vibratory reed which mechanically and magneticallyintegral with said core and which also constitutes said switch, and arelatively l1i rh-l'esistance winding coiled about said armature andinterposed in a permanently closed connection between the track rails atthe last-mentioned end of the track-section, said connection includingthe source of current and the electromagnet winding, but not the switch;substantially as and for the purpose set :torth.

in a railway electric t'aclecircuit which includes on the one hand thewinding oi? a tra[lie-controlling relay interposed in. series betweenthe track-rails at one end of a track-section, and on the other hand asource of continuous current, an electronuurnet winding, and anormally-closed switch controlled thereby, all interposed in seriesbetween the triuzk-rails at the opposite end oi the track-section; thecombina tion of a core lior said electromagnet winding, an armaturetherefor formed by a vi bratory reed which is mechanically andmagnetically integral with said core and which also constitutes saidswitch, and a condenser interposed in a connection in parallel with thatconnection which is normally bridged by the switch; substantially s andfor the purpose forth.

1-. lin a railway electric traclccircuit which. includes on the one handthe winding; of a trallic-controlling relay interposed in series betweenthe track-rails at one end oi:

a track-section, and on the other hand a source of. continuous current,an electrom'an'net winding, and a normally-closed switch controlledthereby, all interposed in series between. the truck-rails at theopposite end oi a traclcsectiou; the combination of a core for saidclecti'oinagnet winding, an armature therefor formed by a vibratory reedwhich is mechanically and mzurnetically integral with said core andwhich also constitutes said switch, a condenser, and a relativelyhinlrresistancc winding coiled about said armature, said condenser andhigh-resistanre winding being interposed in conne ions both o'l whichare in parallel with that connection which is normally bridged by theswitch; substantially as and for the purpose set forth.

5. ln a railway electric track-circuit which includes on the one handthe winding of a tra'liic-controlling relay interposed in series betweenthe track-rails at one end of a track-section, and on the other hand asource of continuous current and an electromagnet winding); bothinterposed in series between the track-rails at the opposite end of thetraclnsection; the combination of a about said switch and interposed init permanently closed connection between the track-rails at saidlast-mentioned end of the ti'aclesection, said permanently closed connection including the source of current and the electromagnet winding;but not the switch; substantially as and for the purpose set forth.

REUBEN WILLIAM TARRANT.

